Unifi: Dead UAP-AC-PRO?

On my way to bed last night, I noticed that two of the smart devices in my office - the lamp and the shelving lighting - were both offline in Home Assistant. Strangely, the Skyfan wasn’t offline, so it took me a moment to figure out what the issue was: the Unifi access point that covers the rear portion of the house had decided to croak on me, and as they were unable to maintain a decent enough connection they were ushered off by the front one, never to be heard from again.

I spent far too long suspecting my patch cables (very cheap Temu things that I admittedly don’t really have any objective complaints about), I slipped a zip-tie under the AP to get it off the ceiling, and replaced it with a spare I had, which came right up. I adopted it, configured it correctly, and went to bed angry.

Over breakfast this morning I was having a read, and found a few threads mentioning a fairly wide-spread problem some 7 years ago, where Unifi were actually RMAing these devices outside of the warranty period, suggesting something they knew about, which was further irritating to me. Continuing my search, I found a reddit thread mention of devices where they failed to negotiate power-over-ethernet with a switch (exactly how mine were hooked up), so on my lunch break I dug out a POE injector and connected it up and yep - it came to life.

I started thinking about whether it’d be possible, or even worth it, to replace the IC responsible for this when I stumbled upon gold: someone’s not only been through this, but they successfully rescued the device by simply removing (not replacing) a single component!

I’ll replicate, tersely, the instructions here as I don’t trust Ubiquiti not to trash the thread - indeed I couldn’t find the linked instructions to open the fucking thing. But in case the thread disappears, the user TomBK on the Unifi community came to my rescue at least:

Verify that the UAP does actually power up via a POE injector, you’re wasting your time if it doesn’t.
Use a plastic spudger to pry it open. There are no screws, there’s five clips and a fuckload of adhesive holding it together. It took more force than you think, but once one clip pops the rest are trivial to undo.
Remove the four screws to liberate the PCB from the back of the case.
Flip the board over, and observe near the USB port. With the USB port oriented towards you, looking at the back side of the board, there is a line of four tiny transistors to the right, and then below it are two capacitors, C406 and C2. They may not be present, if they’re not, you’re wasting your time.
Check the resistance of C2 - if it registers as a short or very low resistance, it’s probably cooked. If it’s open, this is probably not the fault that’s killed your UAP.
Desolder C2 with a decent iron or soldering gun. It’s tiny, so I just used some flux, flooded the tip of the iron, heated it up and pushed it off. I then used more flux and a clean tip to make sure the pads are not bridged, and then verified no short with a multimeter.
Plug the device into a switch and see if it powers on. If it doesn’t, this is probably not the issue that killed your UAP.
Reassemble the device and put it back into service.

I’m not an electronics engineer, so I don’t know if the proposed explanation and solution are sound, but it’s worked for me.

As of the time of writing it’s not skipped a beat for 48 hours, so that’s alright.